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Methodology Object oriented analysis: –a method of analysis in which requirements are examined from the perspective of the classes and objects found in the vocabulary of the problem domain. (Booch) Universe of Discourse –.. the world(or universe) that we are interested in talking (or discoursing) about (Halpin) List concepts and relations Translate into formal language (UML) –Normalized –Explicit –Patterns

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Gerard Lemson, IVOA DM 28/5/2004 Universe of Discourse for VO We want to talk/discourse about the work that astronomers, astrophysicists and support scientists do and the results they have obtained We want to do this in a scientifically rigorous manner

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Gerard Lemson, IVOA DM 28/5/2004 SI http://physics.nist.gov/cuu/Units/introduction.htmlhttp://physics.nist.gov/cuu/Units/introduction.html. A quantity in the general sense is a property ascribed to phenomena, bodies, or substances that can be quantified for, or assigned to, a particular phenomenon, body, or substance. Examples are mass and electric charge. A quantity in the particular sense is a quantifiable or assignable property ascribed to a particular phenomenon, body, or substance. Examples are the mass of the moon and the electric charge of the proton. A physical quantity is a quantity that can be used in the mathematical equations of science and technology. A unit is a particular physical quantity, defined and adopted by convention, with which other particular quantities of the same kind are compared to express their value. The value of a physical quantity is the quantitative expression of a particular physical quantity as the product of a number and a unit, the number being its numerical value. Thus, the numerical value of a particular physical quantity depends on the unit in which it is expressed.